16177772021 has 2 divisors, whose sum is σ = 16177772022. Its totient is φ = 16177772020.

The previous prime is 16177771969. The next prime is 16177772081. The reversal of 16177772021 is 12027777161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14217939121 + 1959832900 = 119239^2 + 44270^2 .

It is an emirp because it is prime and its reverse (12027777161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16177772021 - 2⁶ = 16177771957 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 16177772021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16177772081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8088886010 + 8088886011.

It is an arithmetic number, because the mean of its divisors is an integer number (8088886011).

Almost surely, 2^16177772021 is an apocalyptic number.

It is an amenable number.

16177772021 is a deficient number, since it is larger than the sum of its proper divisors (1).

16177772021 is an equidigital number, since it uses as much as digits as its factorization.

16177772021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 57624, while the sum is 41.

The spelling of 16177772021 in words is "sixteen billion, one hundred seventy-seven million, seven hundred seventy-two thousand, twenty-one".